Questions: Control Arm Rear Bushing, Caster Adjustable

[Acing]

Hey all,

So I have two questions about Caster adjustment rear lower control arm bushings such as these Powerflex ones. Or any of the ones available on the market.

Powerflex Front Control Arm Rear Bushing, Caster Adjustable
Image source whoosh-motorsports.myshopify•com

I do, yes understand how changing the rear mount point of the lower control arm forward within the space of the bushing can add positive caster (which I want more positive caster).

Image source autotrends•org

My First Question is; Are these bushings a press in and then no adjustment. Or can they be adjusted after installation? I'm inclined to believe that once they are installed there is no adjustment, so you better take care and get it perfect.

My Second Question is; Has anyone already installed these or other brands, if so does it provide a noticeable improvement to handling?

Thank you in advance.

 

[Handy Andy]

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You're asking questions that don't have "easy answers" - a gentleman here by the name of @scotman - has worked on the lower arm bushings before.

This thread might help you...
https://www.fordfiesta.org/threads/...ance-oriented-bushing-upgrade.7625/post-16841

The "natural caster" angle for the Fiesta - about 7 degrees Positive - Being at rest and both Front and Rear axles level

There is NO Front toe-in or out.(±0 angle) However Rear Axle Toe in-out may vary by as much a 0.5 ± degrees due to loading - related to ride height - for rear CAMBER is preset and not adjustable per Ford's way of doing things, but that does not mean it's impossible...

The rear Axle is shaped a lot like a Wishbone and has two pivot points on the frame,
in the axis line of the Front to Rear frame.
Two bushings, and their bolted connection point to the Frame truly - no adjustment,
- you have to rely on the SLOP of the bolt to hole bushing clearance in order to affect any effort
to change your "thrust angle"​

​

Many people ask "Why should I care?"

Have they priced Tires lately?

The reason for that type of tilt is for even tire wear if you ROTATE your tires front to back on a regular basis

That way the Tread wear pattern is even and you obtain the best performance for the life if the tire.

To help with trying to fight a crabbing effect - the Thrust angle needs to be fixed (checked so you don't drift and have to constantly correct - caused by loose hardware or a bad bushing on the rear axle) so you don't force yourself to use the steering wheel to constantly correct for high-crown or deep rut roads, being that the Caster/Camber and Toe-in/out are fixed for MOST roads per the vehicle.

What you see from the bottom, note the rear bushing mounts are in the front of this view.

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As long as you keep proper tire size and pressure, and their wheel offsets. Which is a Positive Offset of 45mm. Wider tires generate an offset issue - so someone wanting a wide tire stance would have to use a wider rim and affect offset that way.

Rear camber is NEGATIVE so to help keep the car tracking on the road in turns to help in cornering..

Front Camber is more Positive so to allow for more "knife edge" balance performance in turns - so your steering wheel - even with that Caster angle - is not "heavy" with understeer - trying to pull the wheel back to equilibrium during the turn.

OEM Sway bar uses fixed links, but as you found out, those adjustable ones help with preloading.

The above info is LEGACY for those whom may want to follow this thread and learn a few things about the alignment issues that can arise from trying mods on this beast.

As always - YMMV - specs are not cast in stone - always subject to change...Some settling of contents may have occurred during shipping and handling

 

[scotman]

Caster affects the high speed stability of the vehicle. That’s what predominantly sticks in my mind when I am trying to figure out what is going on with the handling of a vehicle.
The anti sway bars are about controlling lateral weight transfer while the car is cornering. I think of them as a “kind of lever” that transfers force from one side to the other.. cornering force that is transferred to the “less loaded side” is what makes the vehicle corner more flatly. Even though the bars are fully attached to the chassis,ideally, they don’t have any affect on the static alignment of the vehicle as it rolls down a smooth road in a straight line.

 

[Acing]

Handy@Handy Andy
Thanks for the info. Really helped me get a better understanding of the system as a whole.
Also thanks to Sc@scotman I don't know how I missed that thread.

With winter on the horizon I ordered a complete passenger side control arm with both bushings and ball joint included.
I'll toss that on the car when it arrives. Should hold over the winter. Probably do a write up on that.
Previous owner replaced the driver side control arm a year or so back. Kept the old arm and let me have it. Swell guy. So I'll have an extra set of control arms to work with over the winter.